Ophthalmic optical coherence tomography system and method for quick switching to realize anterior and posterior eye segments imaging

ABSTRACT

It is provided an ophthalmic optical coherence tomography system in the invention, the system comprising: an OCT interferometer primary module and a sample arm module, wherein the OCT interferometer primary module comprises an OCT light source, a fiber coupler, a reference arm, a detection module, an X-direction scanning unit, and a Y-direction scanning unit; the sample arm module comprises an anterior eye segment imaging module and a posterior eye segment imaging module; the Y-direction scanning unit is rotatable; when the Y-direction scanning unit is at a first rotation angle, the Y-direction scanning unit reflects the light received by the X-direction scanning unit into the anterior eye segment imaging module; and when the Y-direction scanning unit is at a second rotation angle, the Y-direction scanning unit reflects the light received by the X-direction scanning unit into the posterior eye segment imaging module. It is further provided a method for quick switching to realize anterior and posterior eye segments imaging in the invention, in which imaging at one time and quick switching for locations at different depths can be realized, and on this basis, the eye axial length can be measured accurately.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a national stage application of InternationalApplication No. PCT/CN2012/074577, filed on Apr. 24, 2012, which ishereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The invention relates to opto-electronics technical field, and inparticular, to an ophthalmic optical coherence tomography system and amethod for quick switching to realize anterior and posterior eyesegments imaging.

BACKGROUND OF THE INVENTION

Eye axial length is a primary issue for judging eye ametropia. It isalso an important indication for discriminating true myopia andpseudomyopia, and for computing parameters of an artificial crystal fora cataract operation.

In existing art, methods for measuring an eye axial length includeA-scan ultrasonic measurement and optical measurement. Existing A-scanultrasonic measurement takes advantage of ultrasonic ranging principle.However, it is necessary to directly touch human eye with a probe in theA-scan ultrasonic measurement. Moreover, resolution of A-scan ultrasonicmeasurement is relatively low and thus is incapable of measurement witha sufficient accuracy. In optical measurement, an eye axis length ismeasured based on the theory of dual-wavelength light wave interference.Optical Coherence Tomography (OCT) is a newly developing optical imagingtechnique. Patent CN200710020707.9 discloses a method of measuring aneye axial length with OCT, and eye axial length measurement for humaneye and eyes of various kinds of living animals can be implemented withthis method. However, the inventor, during the practice of theinvention, discovered that the existing art at least has the followingdisadvantages. Firstly, the optical path is adjusted by using a movableprobe moved by a stepping motor to realize imaging of the cornea andfundus. It takes a certain time for the motor to move back and forth.Thus, it is incapable of quickly switching between the anterior andposterior eye segments and realizing real-time imaging. Furthermore,since the measured object will shake its eyes, the measurement of eyeaxial length is inaccurate with a large error. Secondly, the imagingquality is bad due to the fact that the cornea and fundus have differentshapes and it is unable for a single probe to focus at both of the twolocations.

SUMMARY OF THE INVENTION

A technical problem that solved by embodiments of the present inventionis how to provide an ophthalmic optical coherence tomography system anda method of measuring the length of an eye axis, in which imaging at onetime and quick switching for locations at different depths can berealized, and on this basis, the eye axial length can be measuredaccurately.

To solve the above mentioned technical problem, it is provided anophthalmic optical coherence tomography system according to anembodiment of the present invention. The ophthalmic optical coherencetomography system comprises: an ophthalmic optical coherence tomographysystem, comprising: an OCT interferometer primary module and a samplearm module, wherein, the OCT interferometer primary module comprises anOCT light source, a fiber coupler, a reference arm, a detection module,an X-direction scanning unit, and a Y-direction scanning unit; thesample arm module comprises an anterior eye segment imaging module and aposterior eye segment imaging module; and wherein:

light output by the OCT light source is provided to the sample armmodule and the reference arm via the fiber coupler; the reference armreflects the light received by the reference arm to the fiber coupler;the Y-direction scanning unit is rotatable; when the Y-directionscanning unit is at a first rotation angle, the Y-direction scanningunit reflects light received by the X-direction scanning unit into theanterior eye segment imaging module; when the Y-direction scanning unitis at a second rotation angle, the Y-direction scanning unit reflectsthe light received by the X-direction scanning unit into the posterioreye segment imaging module; the fiber coupler receives light scatteredback by the sample arm, and the received light interferes with the lightreflected back by the reference arm; and the detection module is usedfor detecting the interfered light.

Wherein, the anterior eye segment imaging module comprises: atotal-reflection mirror, a rotatable-adjustable total-reflection mirror,a dichroic mirror, and a fundus lens, and wherein:

when the Y-direction scanning unit is rotated at the first rotationangle, the Y-direction scanning unit reflects light transmitted from theX-direction scanning unit to the total-reflection mirror; thetotal-reflection mirror reflects the light to the rotatable-adjustabletotal-reflection mirror; the rotatable-adjustable total-reflectionmirror is rotatably adjusted correspondingly to a rotation of theY-direction scanning unit and cooperates with the Y-direction scanningunit to reflect the light transmitted on the rotatable-adjustabletotal-reflection mirror to the dichroic mirror; the dichroic mirrorreflects the light to the fundus lens; and the light is transmittedthrough the fundus lens into a human eye to be examined.

Wherein, the anterior eye segment imaging module further comprises atleast one relay lens, and wherein:

the at least one relay lens is between the Y-direction scanning unit andthe total-reflection mirror; in this case, when the Y-direction scanningunit is rotated at a first rotation angle, the Y-direction scanning unitreflects the light from the X-direction scanning unit to thetotal-reflection mirror via the relay lens; or

the at least one relay lens is between the total-reflection mirror andthe rotatable-adjustable total-reflection mirror; in this case, thetotal-reflection mirror reflects the light from the X-direction scanningunit to the rotatable-adjustable total-reflection mirror via the relaylens.

Wherein, the posterior eye segment imaging module comprises: an opticalpath adjustment unit, a refraction adjustment unit, arotatable-adjustable total-reflection mirror, a dichroic mirror, and afundus lens, and wherein:

when the Y-direction scanning unit is rotated at a second rotationangle, the Y-direction scanning unit reflects light transmitted from theX-direction scanning unit to the optical path adjustment unit; theoptical path adjustment unit reflects the light to therotatable-adjustable total-reflection mirror via the refractionadjustment unit; the rotatable-adjustable total-reflection mirror isrotatably adjusted correspondingly to the rotation of the Y-directionscanning unit and cooperates with the Y-direction scanning unit toreflect the light transmitted on the rotatable-adjustabletotal-reflection mirror to the dichroic mirror; the dichroic mirrorreflects the light to the fundus lens; and the light is transmittedthrough the fundus lens into the human eye to be examined.

Wherein, the system further comprises:

an iris imaging module, which comprises: a fundus lens, a dichroicmirror, an iris dichroic mirror, an objective lens, and a camera,wherein, when the light output by the light source illuminates a corneaof a human eye to be examined and is reflected on the cornea, thereflected light is transmitted though the fundus lens and the dichroicmirror and reaches the iris dichroic mirror; the iris dichroic mirrorreflects the light to the objective lens; and the reflected light istransmitted to the camera via the objective lens and is imaged by thecamera.

The system further comprising a fixation optical module, wherein:

the fixation optical module comprises: a fixation device, a lens, atotal-reflection mirror, a refraction compensating lens, a dichroicmirror, and a fundus lens; after focalized by the lens, light from thefixation device is reflected to the refraction compensating lens by thetotal-reflection mirror, transmitted to the iris dichroic mirror in theiris imaging module via the refraction compensating lens, transmitted tothe dichroic mirror and the fundus lens through the iris dichroicmirror, and transmitted through the fundus lens into a human eye to beexamined.

Wherein, the optical path adjustment unit comprises fourtotal-reflection mirrors, and wherein two of the total-reflectionmirrors are fixed, and the other two of the total-reflection mirrors areremovable total-reflection mirrors; during adjustment of optical path,the optical path is adjusted by keeping the two of the total-reflectionmirrors fixed and moving the other two removable total-reflectionmirrors.

Wherein, the optical path adjustment unit further comprises twototal-reflection mirrors and a removable retroreflector; duringadjustment of optical path, the optical path is adjusted by keeping thetwo total-reflection mirrors fixed and moving the removableretroreflector.

Wherein, the total-reflection mirror in the Y-direction scanning unit isa galvanometer.

Wherein, the fixation device in the fixation optical module comprises anLCD or an OLED.

Wherein, an adjustment amount of the optical path adjustment unit isobtained by a location sensor, the location sensor being fixed on theremovable total-reflection mirror or the removable retroreflector in theoptical path adjustment unit.

Correspondingly, according to an embodiment of the invention, it is alsoprovided a method for quick switching to realize anterior and posterioreye segments imaging, comprising:

reflecting light transmitted from the X-direction scanning unit to thetotal-reflection mirror with the Y-direction scanning unit when theY-direction scanning unit is rotated at the first rotation angle;reflecting the light to the rotatable-adjustable total-reflection mirrorwith the total-reflection mirror, the rotatable-adjustabletotal-reflection mirror being rotatably adjusted correspondingly to arotation of the Y-direction scanning unit and cooperating with theY-direction scanning unit to reflect the light transmitted on therotatable-adjustable total-reflection mirror to the dichroic mirror;reflecting the light to the fundus lens with the dichroic mirror;transmitting the light through the fundus lens into a human eye to beexamined;

reflecting the light transmitted from the X-direction scanning unit tothe optical path adjustment unit with the Y-direction scanning unit whenthe Y-direction scanning unit is rotated at a second rotation angle;reflecting the light to the rotatable-adjustable total-reflection mirrorvia the refraction adjustment unit with the optical path adjustmentunit, the rotatable-adjustable total-reflection mirror being rotatablyadjusted correspondingly to the rotation of the Y-direction scanningunit and cooperating with the Y-direction scanning unit to reflect thelight transmitted on the rotatable-adjustable total-reflection mirror tothe dichroic mirror; reflecting the light to the fundus lens with thedichroic mirror; and transmitting the light through the fundus lens intothe human eye to be examined.

Wherein, the method comprises:

when the system is performing anterior eye segment imaging, obtaining anoptical path length that light travels after leaving the fiber andbefore reaching a cornea of the human eye to be examined in the anterioreye segment imaging, the optical path length being a fixed length ofanterior eye segment optical path plus a distance A between a peak ofthe cornea and a peak of image in an OCT image of anterior eye segment,wherein the fixed length of anterior eye segment optical path is anintrinsic parameter of the system, and the distance A between the peakof the cornea and the peak of image in the OCT image of anterior eyesegment is obtained by analyzing the OCT image;

when the system is performing posterior eye segment imaging, obtainingan optical path length that light travels after leaving the fiber andbefore reaching a retina of the human eye to be examined in theposterior eye segment imaging, the optical path length being a fixedlength of posterior eye segment optical path plus an optical pathadjustment amount plus a distance B between a peak of image and a maculafovea in an OCT image of posterior eye segment, wherein the fixed lengthof posterior eye segment optical path is an intrinsic parameter of thesystem, and the distance B between the peak of image and the maculafovea in the OCT image of posterior eye segment is obtained by analyzingthe OCT image;

calculating the difference between the optical path length obtained inanterior eye segment imaging and the optical path length obtained inposterior eye segment imaging, and obtaining an optical length ofexamined eye axis, wherein the optical length of eye axis is: (the fixedlength of posterior eye segment optical path plus an optical pathadjustment amount plus the distance B between the peak of image and themacula fovea in the OCT image of posterior eye segment) minus (the fixedlength of anterior eye segment optical path plus the distance A betweenthe peak of the cornea and the peak of image in the OCT image ofanterior eye segment).

Wherein, the method comprises:

when the system is performing anterior eye segment imaging, collectingan anterior surface of corneal in a cornea image in the anterior eyesegment imaging optical path, and changing the length of posterior eyesegment imaging optical path by adjusting a removable total-reflectionmirror or a removable retroreflector in the optical path adjustmentunit, so that a surface of crystalline lens is measured to obtain anoptical depth of anterior chamber, the optical depth of anterior chamberbeing a distance between the cornea and an anterior surface ofcrystalline lens, wherein the anterior surface of corneal is obtainedwith a anterior eye segment imaging system and the anterior surface ofcrystalline lens is obtained with a posterior eye segment imagingsystem.

Wherein, the method comprises:

when the system is performing anterior eye segment imaging, collecting acornea image in the anterior eye segment imaging module; changing anoptical path of posterior eye segment imaging module by adjusting aremovable total-reflection mirror or a removable retroreflector in theoptical path adjustment unit, so that a posterior surface of crystallinelens is measured with the posterior eye segment imaging module;obtaining a distance between the cornea and the posterior surface ofcrystalline lens; and obtaining an optical thickness of the crystallinelens by subtracting the distance by the optical depth of anteriorchamber; or

scanning an anterior surface of crystalline lens with the anterior eyesegment imaging module and concurrently collecting the posterior surfaceof crystalline lens with the posterior eye segment imaging module, toobtain the optical thickness of the crystalline lens, the opticalthickness of the crystalline lens being equal to subtracting theposterior surface of crystalline lens collected with the posterior eyesegment imaging module by the anterior surface of crystalline lensscanned with the anterior eye segment imaging module.

In implementation of the invention, quick switch and real-time image forlocations at different depths can be realized. On one hand, with anability of quick switch, objects at different depths can be measured,and the detection scope of the OCT system can be enhanced. The switchsystem is able to work stably and change positions accurately withoutinfluencing the signal-to-noise ratio of the system. On the other hand,the light beam can be respectively focalized at different locations.Thus, high quality of anterior and posterior eye segments imaging can beachieved with a relatively high lateral resolution for human eyes havingdifferent ametropia.

Furthermore, based on the anterior and posterior eye segments imaging,an ability of real-time eye axial length measurement can be added.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to illustrate the embodiments or existing technical solutionsmore clearly, a brief description of drawings that assists thedescription of embodiments of the invention or existing art will beprovided below. It would be apparent that the drawings in the followingdescription are only for some embodiments of the invention. A personhaving ordinary skills in the art will be able to obtain other drawingson the basis of these drawings without paying any creative work.

FIG. 1 is a first schematic structural diagram of an ophthalmic opticalcoherence tomography system according to an embodiment of the invention;

FIG. 2 is a schematic structural diagram of a module for realizinganterior eye segment imaging in an ophthalmic optical coherencetomography system according to an embodiment of the invention;

FIG. 3 is a schematic structural diagram of a module for realizingposterior eye segment imaging in an ophthalmic optical coherencetomography system according to an embodiment of the invention;

FIG. 4 is a schematic structural diagram of an iris imaging module in anophthalmic optical coherence tomography system according to anembodiment of the invention;

FIG. 5 is a schematic structural diagram of a fixation optical module inan ophthalmic optical coherence tomography system according to anembodiment of the invention;

FIG. 6 is a schematic diagram of a method for quick switching to realizeanterior and posterior eye segments imaging according to an embodimentof the invention;

FIG. 7 is a schematic diagram of a structure for eye axial lengthmeasurement based on quick switching between anterior and posterior eyesegments imaging according to an embodiment of the invention.

FIG. 8 is a schematic diagram of a method for eye axial lengthmeasurement based on quick switching between anterior and posterior eyesegments imaging according to an embodiment of the invention.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

Technical solutions in embodiments of the present invention will beillustrated clearly and entirely with the aid of the drawings in theembodiments of the invention. It is apparent that the illustratedembodiments are only some embodiments of the invention instead of all ofthem. Other embodiments that a person having ordinary skills in the artobtains based on the illustrated embodiments of the invention withoutpaying any creative work should all be within the protection scopesought by the present invention.

FIG. 1 is a first schematic structural diagram of an ophthalmic opticalcoherence tomography system according to an embodiment of the invention.As shown in FIG. 1, the ophthalmic optical coherence tomography systemcomprises: an ophthalmic optical coherence tomography (OCT)interferometer primary module and a sample arm module. The OCTinterferometer primary module includes an OCT light source 101, a fibercoupler 102, a reference arm 104, a detection module 106, an X-directionscanning unit 109, and a Y-direction scanning unit 110. The sample armmodule comprises an anterior eye segment imaging module and a posterioreye segment imaging module.

Light output by the OCT light source 101 is provided to the sample armmodule and the reference arm 104 via the fiber coupler 102. Thereference arm 104 reflects the received light by it to the fiber coupler102. The X-direction scanning unit 109 receives the light output by theOCT light source 101, and the Y-direction scanning unit 110 isrotatable. When the Y-direction scanning unit 110 is at a first rotationangle, it reflects the light received by the X-direction scanning unit109 into the anterior eye segment imaging module. When the Y-directionscanning unit 110 is at a second rotation angle, it reflects the lightreceived by the X-direction scanning unit 109 into the posterior eyesegment imaging module. The fiber coupler 102 receives light scatteredback by the sample arm, and the received light interferes with the lightreflected by the reference arm 104. The detection module 106 is used fordetecting the interfered light, which will be processed and displayed bythe computer 107.

Specifically, in one embodiment of the invention, when the OCT lightsource 101 is a low coherence light source, the detector in thedetection module 106 is a spectrometer (the system is a frequency domainOCT); and when the OCT light source 101 is a frequency sweep lightsource, the detector is a high-speed photoelectric detector (the systemis a frequency sweep OCT). The reference arm 104 includes a referencemirror 105 and a collimating lens 108, wherein, in the reference arm104, the reference mirror 105 reflects the received light output by theOCT light source back to the fiber coupler 102. The collimating lens 108routes the light output by the OCT light source 10 to the X-directionscanning unit 109. The Y-direction scanning unit 110 is rotatable. Withthe rotation of the Y-direction scanning unit 110, the light from theX-direction scanning unit 109 is reflected to an imaging modulecorresponding to the rotation angle. That is, when the Y-directionscanning unit 110 is at a first rotation angle, the light received bythe X-direction scanning unit 109 is reflected into the anterior eyesegment imaging module; and when the Y-direction scanning unit 110 is ata second rotation angle, the light received by the X-direction scanningunit 109 is reflected into the posterior eye segment imaging module. TheOCT interferometer primary module further comprises a polarizationcontroller 103, which is connected with the fiber coupler 102 and usedfor receiving the light reflected back by the sample arm module andtransmitting it to the fiber coupler 102.

It should be made clear that the sample arm module includes the anterioreye segment imaging module and the posterior eye segment imaging module,wherein the anterior eye segment imaging module comprises: atotal-reflection mirror 202, a rotatable-adjustable total-reflectionmirror 401, a dichroic mirror 402, and a fundus lens 403. When rotatedat the first rotation angle, the Y-direction scanning unit 110 reflectsthe light from the X-direction scanning unit 109 back to thetotal-reflection mirror 202. Then, the light is reflected to therotatable-adjustable total-reflection mirror 401 by the total-reflectionmirror 202. The rotatable-adjustable total-reflection mirror 401 isrotatably adjusted correspondingly to the rotation of the Y-directionscanning unit 110 and cooperates with the Y-direction scanning unit 110to reflect the light sent on the rotatable-adjustable total-reflectionmirror 401 to the dichroic mirror 402. The light is then reflected tothe fundus lens 403 by the dichroic mirror 402 and transmitted throughthe fundus lens 403 into a human eye E which is to be examined.

It should be made clear that the sample arm module includes the anterioreye segment imaging module and the posterior eye segment imaging module.The posterior eye segment imaging module comprises therotatable-adjustable total-reflection mirror 401, the dichroic mirror402, and the fundus lens 403 which has been included in the anterior eyesegment imaging module. Further, the posterior eye segment imagingmodule additionally comprises an optical path adjustment unit and arefraction adjustment unit 305. When rotated at the second rotationangle, the Y-direction scanning unit 110 reflects the light from theX-direction scanning unit 109 to a first total-reflection mirror 301 inthe optical path adjustment unit. Then, reflected by the secondtotal-reflection mirror 302, the third total-reflection mirror 303, andthe fourth total-reflection mirror 304, the light is reflected by theoptical path adjustment unit and transmitted to the rotatable-adjustabletotal-reflection mirror 401 via the refraction adjustment unit 305. Therotatable-adjustable total-reflection mirror 401 is rotatedcorrespondingly to the rotated angle of the Y-direction scanning unit110 and cooperates with the Y-direction scanning unit 110 to reflect thelight transmitted on the rotatable-adjustable total-reflection mirror401 to the dichroic mirror 402. The light is then reflected to thefundus lens 403 by the dichroic mirror 402 and transmitted through thefundus lens 403 into the human eye E to be examined.

It should be made clear that the anterior eye segment imaging module andthe posterior eye segment imaging module share the samerotatable-adjustable total-reflection mirror 401, dichroic mirror 402,and fundus lens 403.

It should be made clear that the ophthalmic optical coherence tomographysystem further includes an iris imaging module which comprises: an irisdichroic mirror 501, an objective lens 502, and a camera 503. When thelight from the light source illuminates the cornea of a human eye to beexamined and is reflected on the cornea, the reflected light travelsthough the fundus lens 403 and the dichroic mirror 402 and reaches theiris dichroic mirror 501. The iris dichroic mirror 501 reflects thelight to the objective lens 502. The reflected light is than transmittedto the camera 503 via the objective lens 502 and is imaged by the camera503.

It should be made clear that the ophthalmic optical coherence tomographysystem further includes a fixation optical module which comprises: afixation device 601, a lens 602, a total-reflection mirror 603, and arefraction compensating lens 604. After focalized by the lens 602, lightfrom the fixation device 601 is reflected to the refraction compensatinglens 604 by the total-reflection mirror 603. Then, the light istransmitted to the iris dichroic mirror 501 via the refractioncompensating lens 604, routed to the dichroic mirror 402 and the funduslens 403 through the iris dichroic mirror 501, and transmitted throughthe fundus lens 403 into the human eye to be examined.

The ophthalmic optical coherence tomography system provided in oneembodiment of the invention can achieve not only posterior eye segmentimaging but also anterior eye segment imaging. With the Y-directionscanning unit 110 cooperating with the rotatable-adjustabletotal-reflection mirror 401, namely, the rotatable-adjustabletotal-reflection mirror 401 is rotated simultaneously andcorrespondingly with the rotation of the Y-direction scanning unit 110,a quick, accurate, and real-time imaging of locations at differentdepths can be achieved as well as switching between anterior andposterior segments imaging systems. Furthermore, a function of measuringthe eye axial length can be added on the basis of achieving imaging ofanterior eye segment and posterior eye segment.

FIG. 2 is a schematic structural diagram of a module for realizinganterior eye segment imaging in an ophthalmic optical coherencetomography system according to an embodiment of the invention. As shownin FIG. 2, the anterior eye segment imaging module comprises: atotal-reflection mirror 202, a rotatable-adjustable total-reflectionmirror 401, a dichroic mirror 402, and a fundus lens 403. When rotatedat the first rotation angle, the Y-direction scanning unit 110 reflectsthe light from the X-direction scanning unit 109 back to thetotal-reflection mirror 202. Then, the light is reflected to therotatable-adjustable total-reflection mirror 401 by the total-reflectionmirror 202. The rotatable-adjustable total-reflection mirror 401 isrotatably adjusted correspondingly to the rotation of the Y-directionscanning unit 110 and cooperates with the Y-direction scanning unit 110to reflect the light sent on the rotatable-adjustable total-reflectionmirror 401 to the dichroic mirror 402. The light is then reflected tothe fundus lens 403 by the dichroic mirror 402 and transmitted throughthe fundus lens 403 into a human eye E which is to be examined.

It should be made clear that the anterior eye segment imaging modulefurther comprises at least one relay lens.

Wherein, there is at least one relay lens between the Y-directionscanning unit 110 and the total-reflection mirror 202. In this case,when Y-direction scanning unit 110 is rotated at the first rotationangle, the Y-direction scanning unit reflects the light from theX-direction scanning unit 109 to the total-reflection mirror 202 via therelay lens.

Optionally, there is at least one relay lens between thetotal-reflection mirror 202 and the rotatable-adjustabletotal-reflection mirror 401. In this case, the total-reflection mirror202 reflects the light from the X-direction scanning unit 109 to therotatable-adjustable total-reflection mirror 401 via the relay lens.

In one embodiment of the invention, preferably, the anterior eye segmentimaging optical path comprises two relay lenses, i.e. a first relay lens201 and a second relay lens 203. The first relay lens 201 is between thetotal-reflection mirror 202 and the Y-direction scanning unit 110, andthe second relay lens 203 is between the total-reflection mirror 202 andthe rotatable-adjustable total-reflection mirror 401. In this case, whenrotated at the first rotation angle, the Y-direction scanning unit 110reflects the light from the X-direction scanning unit 109 to thetotal-reflection mirror 202 via the first relay lens 201. Then, thelight is reflected by the total-reflection mirror 202, transmittedthrough the second relay lens 203, and transmitted to therotatable-adjustable total-reflection mirror 401. The light is thenreflected to the fundus lens 403 by the dichroic mirror 402. In the end,the light travels through the human eye E and is focalized at thefundus.

Specifically, in one embodiment of the invention, therotatable-adjustable total-reflection mirror 401 and the Y-directionscanning unit 110 are concurrently controlled by a computer. TheY-direction scanning unit is controlled by the computer to rotate at thefirst rotation angle. Here, the orientation of the Y-direction scanningunit is able to exactly make the angle between an incident light and areflected light to be β. Concurrently, the computer controls therotatable-adjustable total-reflection mirror 401 to rotatecorrespondingly to the first rotation angle of the Y-direction scanningunit 110 and to cooperate with the Y-direction scanning unit to realizeanterior eye segment imaging. After routed through the Y-directionscanning unit 110, the light is transmitted to the total-reflectionmirror 202 via the first relay lens 201. Then, the light is reflected bythe total-reflection mirror 202, transmitted through the second relaylens 203, and transmitted to the rotatable-adjustable total-reflectionmirror 401. The light is then reflected to the fundus lens 403 by thedichroic mirror 402. In the end, the light travels through the human eyeE and is focalized at the fundus.

It should be make clear that, in one embodiment of the invention, theY-direction scanning unit 110 serves not only to scan in one dimensionalbut also to switch the optical path. In one embodiment of the invention,the Y-direction scanning unit 110 is a galvanometer or utilizes otherhigh-accuracy orientation mechanism, so that the need of quick switchbetween optical paths in the system can be satisfied. When measuring thefundus, by rotating the Y-direction scanning unit 110, the optical pathis reflected to the total-reflection mirror 301 from the X-directionscanning unit 109 and the light turns for an angle of α. When measuringthe cornea, by rotating the Y-direction scanning unit 110, the opticalpath is reflected to the first relay lens 201 from the X-directionscanning unit 109 and the light turns for an angle of β. Therotatable-adjustable total-reflection mirror 401 is rotatedcorrespondingly to the rotation of the Y-direction scanning unit 110.The Y-direction scanning unit 110 and the rotatable-adjustabletotal-reflection mirror 401 cooperates with each other so that the quickswitch between the anterior and posterior eye segment imaging opticalpaths can be realized.

FIG. 3 is a schematic structural diagram of a module for realizingposterior eye segment imaging in an ophthalmic optical coherencetomography system according to an embodiment of the invention. As shownin FIG. 3, the posterior eye segment imaging module comprises therotatable-adjustable total-reflection mirror 401, the dichroic mirror402, and the fundus lens 403 which has been included in the anterior eyesegment imaging module. Further, the posterior eye segment imagingmodule additionally comprises an optical path adjustment unit and arefraction adjustment unit 305. When rotated at the second rotationangle, the Y-direction scanning unit 110 reflects the light from theX-direction scanning unit 109 to a first total-reflection mirror 301 inthe optical path adjustment unit. Then, reflected by the secondtotal-reflection mirror 302, the third total-reflection mirror 303, andthe fourth total-reflection mirror 304, the light is reflected by theoptical path adjustment unit and transmitted to the rotatable-adjustabletotal-reflection mirror 401 via the refraction adjustment unit 305. Therotatable-adjustable total-reflection mirror 401 and the Y-directionscanning unit 110 cooperates with each other to accomplish the posterioreye segment imaging module.

Specifically, the rotatable-adjustable total-reflection mirror 401 andthe Y-direction scanning unit 110 are concurrently controlled by acomputer. When the Y-direction scanning unit 110 is rotated at thesecond rotation angle, the rotatable-adjustable total-reflection mirror401 is correspondingly rotated at the same time. That is, therotatable-adjustable total-reflection mirrors 401 and the Y-directionscanning unit 110 cooperates with each other to accomplish the posterioreye segment imaging module. In one embodiment of the invention, theY-direction scanning unit is controlled by the computer to rotate at thesecond rotation angle. Here, the orientation of the Y-direction scanningunit is able to exactly make the angle between an incident light and areflected light to be a. Light transmitted from the X-direction scanningunit 109 is reflected to the first total-reflection mirror 301 by theY-direction scanning unit 110. Then, the light is reflected by thesecond total-reflection mirror 302, the third total-reflection mirror303, and the fourth total-reflection mirror 304. Such that, the light isreflected to the rotatable-adjustable total-reflection mirror 401 viathe refraction adjustment unit 305 by the fourth total-reflection mirror304. The light is then reflected to the fundus lens 403 via the dichroicmirror 402. That is, during the OCT imaging of fundus, it is requiredthat the OCT light beam is localized at the fundus when the scanninggalvanometer is motionless and the central light beam of the scanninglight beam is focalized at the pupil when the galvanometer is scanning.

It should be made clear that, when measuring the fundus, since differenthuman eyes have different eye axial lengths but the reference arm 104 inthe OCT imaging module is unadjustable, it is necessary to incorporatean optical path adjustment unit into the optical path for fundus in theposterior eye segment imaging module. If the optical path adjustmentmechanism is implemented by, for example, a stepping motor moving backand forth or other ways, before the two-dimensional galvanometer in theoptical path adjustment unit, it is the mechanical system movement tochange the optical path. This will introduce Doppler Effect and thusreduce the signal-to-noise ratio of the system. In order to solve thisproblem, the optical path adjustment unit is added into the optical pathof fundus after the two-dimensional galvanometer in the optical pathadjustment unit in the invention. The optical path adjustment unitcomprises four total-reflection mirrors, and wherein two of thetotal-reflection mirrors are fixed, and the other two of thetotal-reflection mirrors are removable total-reflection mirrors. Thatis, the first total-reflection mirror 301 and the fourthtotal-reflection mirror 304 are fixed, while the second total-reflectionmirror 302 and the third total-reflection mirror 303 are movabletotal-reflection mirrors. During adjustment of optical path, the opticalpath is adjusted by keeping the two of the total-reflection mirrorsfixed, namely, keeping the first total-reflection mirror 301 and thefourth total-reflection mirror 304 fixed, and moving the other tworemovable total-reflection mirrors, namely, moving the secondtotal-reflection mirror 302 and the third total-reflection mirror 303,so that, for different human eyes, by adjusting the removabletotal-reflection mirrors, i.e. the second total-reflection mirror 302and the third total-reflection mirror 303 and determining the lengthdifference between the optical paths for anterior and posterior eyesegments, Doppler Effect would not be introduced when performing thequick switching.

On the other hand, in one embodiment of the invention, the optical pathadjustment unit further comprises two total-reflection mirrors and aremovable retroreflector; during adjustment of optical path, the opticalpath is adjusted by keeping the two total-reflection mirrors fixed andmoving the removable retroreflector

FIG. 4 is a schematic structural diagram of an iris imaging module in anophthalmic optical coherence tomography system according to anembodiment of the invention. As shown in FIG. 4, the iris imaging modulecomprises a fundus lens 403, a dichroic mirror 402, an iris dichroicmirror 501, an objective lens 502, and a camera 503, wherein, when thelight output by the light source illuminates a cornea of a human eye Eto be examined and is reflected on the cornea, the reflected light istransmitted though the fundus lens 403 and the dichroic mirror 402 andreaches the iris dichroic mirror 501; the iris dichroic mirror 501reflects the light to the objective lens 502; and the reflected light istransmitted to the camera 503 via the objective lens 502 and is imagedby the camera 503.

Specifically, a monitor optical path in the iris imaging module guidesthe doctor to operate the instrument and know information related to theperson being examined. A chin support system is used to keep the eyebeing examined fixed and make the fixation mark from the fixationoptical module to be fixed seen in the eye E being examined. Theexaminee is observing the display of the computer 107 in the OCTinterferometer primary module while controlling the movement of the chinsupport system with a joystick, so that the cornea of the eye E beingexamined can be taken by the camera 503 in the iris imaging module andan image of the cornea is shown in the display of the computer 107 inthe OCT interferometer primary module to direct the doctor to operatethe instrument and know information related to the human eye beingexamined.

It should be made clear that the iris dichroic mirror 501 can not onlyreflect the illuminating light from the illuminating light source in theiris imaging module but also transmit the fixation light output by thefixation device 601 in the fixation optical module.

It should be made clear that the light output by the illuminating lightsource can be near-infrared light with a wavelength of 780 nm.

FIG. 5 is a schematic structural diagram of a fixation optical module inan ophthalmic optical coherence tomography system according to anembodiment of the invention. As shown in FIG. 5, the fixation opticalmodule comprises: a fixation device 601, a lens 602, a total-reflectionmirror 603, a refraction compensating lens 604, a dichroic mirror 402,and a fundus lens 403. The light from the fixation device 601 isfocalized by the lens 602, reflected to the refraction compensating lens604 by the total-reflection mirror 603, transmitted to the iris dichroicmirror 501 in the iris imaging module via the refraction compensatinglens 604, routed to the dichroic mirror 402 and the fundus lens 403through the iris dichroic mirror 501, and transmitted into the human eyeE to be examined via the fundus lens 403.

Specifically, in an embodiment of the invention, an internal fixationmark can be used to change the fixation position of the human eye E tobe examined. The internal fixation mark can be moved up and down, leftand right, to meet the examining requirement of the human eye atdifferent positions. When implementing posterior eye segment imaging,the refraction adjustment unit 305 in the posterior eye segment imagingmodule and the refraction compensating lens 604 in the fixation opticalmodule can be concurrently controlled by a computer.

If the fixation point is fixed and does not move, the clarity of thefixation point is different for different human eyes, causing theexamined human uncomfortable during the eye fixation. Thus, after therefraction of OCT light path in the posterior eye segment imaging moduleis adjusted by the refraction adjustment unit 305, the light path can befocalized on the fundus retina, which enables the human eye to see thescanning line clearly.

In an embodiment of the invention, in order for different human eyes tosee clearly the scanning line, a refraction adjustment mechanism isintroduced for the fixation point by the refraction compensating lens604 in the fixation optical module, for the sole sake that differenthuman eyes can see clearly. However, if the fixation optical path isadded after the refraction adjustment unit 305 in the posterior eyesegment imaging module, the OCT opitcal path in the posterior eyesegment imaging module will be influenced, because the fixation pointcannot move together with the four total-reflection mirrors in theoptical path adjustment unit. Thus, the fixation optical path isdefinitely placed before the four total-reflection mirrors in theoptical path adjustment unit. In one embodiment of the invention, therefraction adjustment unit 305 in the posterior eye segment imagingmodule and the refraction compensating lens 604 in the fixation opticalmodule are concurrently moved by control of a computer to realize aco-moving mechanism between the refraction adjustment unit 305 and therefraction compensating lens 604. By moving concurrently the refractionadjustment unit 305 in the posterior eye segment imaging module and therefraction compensating lens 604 in the fixation optical module by thecontrol of the computer, the fixation of human eye can be realized whilethe OCT optical path of the posterior eye segment imaging module wouldnot be influenced.

It should be made clear that the fixation light output by the fixationdevice 601 in the fixation optical module can be visible light with awavelength of 780 nm.

It should be made clear that the fixation device 601 in the fixationoptical module comprises LCD or OLCD.

FIG. 6 is a schematic diagram of a method of quick switching forrealizing anterior and posterior eye segments imaging according to anembodiment of the invention. As shown in FIG. 6, the method comprisesthe following steps.

S101, when the Y-direction scanning unit is rotated at the firstrotation angle, the Y-direction scanning unit reflects light transmittedfrom the X-direction scanning unit to the total-reflection mirror, whichthen reflects the light to the rotatable-adjustable total-reflectionmirror. The rotatable-adjustable total-reflection mirror is rotatablyadjusted according to the rotation of the Y-direction scanning unit andcooperates with the X-direction scanning unit to reflect the lighttransmitted on the rotatable-adjustable total-reflection mirror to thedichroic mirror. The light is then reflected to the fundus lens by thedichroic mirror and routed into the human eye E to be examined via thefundus lens.

Specifically, in one embodiment of the invention, therotatable-adjustable total-reflection mirror 401 and the Y-directionscanning unit 110 are concurrently controlled by a computer. TheY-direction scanning unit is controlled by the computer to rotate at thefirst rotation angle. Here, the orientation of the Y-direction scanningunit is able to exactly make the angle between an incident light and areflected light to be β. Concurrently, the computer controls therotatable-adjustable total-reflection mirror 401 to rotatecorrespondingly to the first rotation angle of the Y-direction scanningunit 110 and to cooperate with the Y-direction scanning unit to realizeanterior eye segment imaging. By rotating the Y-direction scanning unit110, the light is transmitted to the total-reflection mirror 202 via thefirst relay lens 201 after it is routed through the Y-direction scanningunit. Then, the light is reflected by the total-reflection mirror 202,transmitted through the second relay lens 203, and transmitted to therotatable-adjustable total-reflection mirror 401. The light is thenreflected to the fundus lens 403 by the dichroic mirror 402. In the end,the light is routed through the human eye E and is focalized at thefundus.

S102, when the Y-direction scanning unit is rotated at the second angle,it reflects the light transmitted from the X-direction scanning unitinto the optical path adjustment unit. The optical path adjustment unitreflects the light to the rotatable-adjustable total-reflection mirrorvia the refraction adjustment unit. The rotatable-adjustabletotal-reflection mirror is rotatably adjusted correspondingly to therotation of the Y-direction scanning unit and cooperates with theY-direction scanning unit to reflect the light transmitted on therotatable-adjustable total-reflection mirror to the dichroic mirror. Thelight is then reflected to the fundus lens by the dichroic mirror androuted into the human eye E to be examined via the fundus lens.

Specifically, in one embodiment of the invention, therotatable-adjustable total-reflection mirror 401 and the Y-directionscanning unit 110 are concurrently controlled by a computer. TheY-direction scanning unit is controlled by the computer to rotate at thesecond rotation angle. Here, the orientation of the Y-direction scanningunit is able to exactly make the angle between an incident light and areflected light to be a. In the posterior eye segment imaging, it isrequired that the OCT light beam is focalized at the fundus when thescanning galvanometer is resting. Light transmitted from the X-directionscanning unit 109 is reflected to the optical path adjustment unit bythe Y-direction scanning unit 110. Then, the light is reflected to therotatable-adjustable total-reflection mirror 401 via the refractionadjustment unit 305 by the f optical path adjustment unit. Therotatable-adjustable total-reflection mirror 401 is rotatedcorrespondingly to the second angle at which the Y-direction scanningunit 110 is rotated and cooperates with the Y-direction scanning unit110 to implement the posterior eye segment imaging, reflecting the lighttransmitted on the rotatable-adjustable total-reflection mirror 401 tothe dichroic mirror 402. The light is then reflected to the fundus lensby the dichroic mirror 402, routed through the human eye E, andfocalized at the pupil of the human eye.

In one embodiment of the invention, the switch between the anterior andposterior eye segment optical paths is realized by mutual cooperation ofthe Y-direction scanning unit and the rotatable-adjustabletotal-reflection mirror.

FIG. 8 is a schematic diagram of eye axial length measurement based onquick switching between anterior and posterior eye segments imagingaccording to an embodiment of the invention. The method for measuringthe eye axial length comprising the following steps.

S201, when the system is performing anterior eye segment imaging, anoptical path length that light travels after leaving the fiber andbefore reaching a cornea of the human eye to be examined in the anterioreye segment imaging is obtained, the optical path length being a fixedlength of anterior eye segment optical path plus a distance A between apeak of the cornea and a peak of image in an OCT image of anterior eyesegment, wherein the fixed length of anterior eye segment optical pathis an intrinsic parameter of the system, and the distance A between thepeak of the cornea and the peak of image in the OCT image of anterioreye segment is obtained by analyzing the OCT image.

Specifically, when anterior eye segment imaging is implemented in thesystem according to one embodiment of the invention, therotatable-adjustable total-reflection mirror 401 is rotatedcorrespondingly to the first angle at which the Y-direction scanningunit is rotated and cooperates with the Y-direction scanning unit torealize the anterior eye segment imaging. The light beam is routedthrough the Y-direction scanning unit, transmitted to thetotal-reflection mirror 202 via the first relay lens 201, reflected tothe rotatable-adjustable total-reflection mirror 401 via the secondrelay lens 203 by the total-reflection mirror 202, reflected to thefundus lens 403 via the dichroic mirror 402, and transmitted into thehuman eye E in the end. The optical path length that light travels afterleaving the fiber and before reaching a cornea of the human eye to beexamined is a fixed length of anterior eye segment optical path plus adistance A between a peak of the cornea and a peak of image in an OCTimage of anterior eye segment, wherein the fixed length of anterior eyesegment optical path is an intrinsic parameter of the system, and thedistance A between the peak of the cornea and the peak of image in theOCT image of anterior eye segment is obtained by analyzing the OCTimage. When anterior eye segment imaging is implemented in the systemaccording to one embodiment of the invention, the aplanatic plane of theanterior eye segment imaging optical path locates at F in FIG. 8.

S202, when the system is performing posterior eye segment imaging, anoptical path length that light travels after leaving the fiber andbefore reaching a retina of the human eye to be examined in theposterior eye segment imaging is obtained, the optical path length beinga fixed length of posterior eye segment optical path plus an opticalpath adjustment amount plus a distance B between a peak of image and amacula fovea in an OCT image of posterior eye segment, wherein the fixedlength of posterior eye segment optical path is an intrinsic parameterof the system, and the distance B between the peak of image and themacula fovea in the OCT image of posterior eye segment is obtained byanalyzing the OCT image.

Specifically, when anterior eye segment imaging is implemented in thesystem according to one embodiment of the invention, the Y-directionscanning unit reflects the light transmitted from the X-directionscanning unit to the optical path adjustment unit. The light is thenreflected to the rotatable-adjustable total-reflection mirror 401 viathe refraction adjustment unit 305 by the optical path adjustment unit,reflected to the fundus 403 via the dichroic mirror 402, transmittedinto the human eye E, and focalized at the pupil of the human eye E. Theoptical path length that light travels after leaving the fiber andbefore reaching a retina of the human eye to be examined in theposterior eye segment imaging is a fixed length of posterior eye segmentoptical path plus an optical path adjustment amount plus a distance Bbetween a peak of image and a macula fovea in an OCT image of posterioreye segment, wherein the fixed length of posterior eye segment opticalpath is an intrinsic parameter of the system, and the distance B betweenthe peak of image and the macula fovea in the OCT image of posterior eyesegment is obtained by analyzing the OCT image. The aplanatic plane ofthe posterior eye segment imaging optical path locates at G in FIG. 8,and the aplanatic plane of the fundus optical path locates at H in FIG.8.

S203, a difference between the optical path length obtained in anterioreye segment imaging and the optical path length obtained in posterioreye segment imaging is calculated, and an optical length of examined eyeaxis is obtained, wherein the optical length of eye axis is: (the fixedlength of posterior eye segment optical path plus an optical pathadjustment amount plus the distance B between the peak of image and themacula fovea in the OCT image of posterior eye segment) minus (the fixedlength of anterior eye segment optical path plus the distance A betweenthe peak of the cornea and the peak of image in the OCT image ofanterior eye segment). Based on the optical length of eye axis, thelength of the eye axis may be obtained, namely, the length of the eyeaxis is equal to the optical length of eye axis divided by therefractive index of the eye.

Specifically, in one embodiment of the invention, when the removabletotal-reflection mirrors 302 and 303 are at original positions, theoptical path difference between the aplanatic plane (at location G inFIG. 8) of the fundus optical path and the aplanatic plane (at locationF in FIG. 8) of the anterior eye segment imaging optical path is C0,which can be measured by calibrations. Axis lengths of different humanbeings are different. When implementing OCT imaging of the fundus, theaplanatic plane of fundus imaging optical path locates at position G inFIG. 8. Fundus imaging for different human eyes are realized by movingthe removable total-reflection mirrors 302 and 303 up-and-down. Hence,when the total-reflection mirrors 302 and 303 are concurrently downmoved for a distance X, the position of the aplanatic plane of fundusimaging optical path is changed from 306 to 307, varying for a distance2X.

In one embodiment of the invention, measurement of axis length isrealized based on anterior and posterior eye segments imaging. Steps ofthe measurement of axis length are illustrated in FIGS. 7 and 8. FIG. 7comprises the following: the peak K of the cornea in the anterior eyesegment OCT image, the peak D of image in the anterior eye segment OCTimage, the distance A between the peak of the cornea and the peak ofimage in the anterior eye segment OCT image, the peak E of image in theposterior eye segment OCT image, the macula fovea I in the posterior eyesegment OCT image, and the distance B between the peak of image and themacula fovea in the posterior eye segment OCT image. The specificoperation steps are as below: firstly, the removable total-reflectionmirrors 302 and 303 are reset. Here, the fixed difference betweenoptical paths for anterior and posterior eye segments is C0, which isobtained by calibrations. That is, by resetting the removabletotal-reflection mirrors 302 and 303 to quick switch between anteriorand posterior eye segments optical paths and to move the examined objectback-and-forth, the OCT signals of the object is located at the sameposition in the anterior and posterior eye segment OCT images, namely,distances of the interference planes from the peaks of images are thesame. By measuring the back-and-forth movement amount of the object,calibrations can be determined to obtain the value of the fixeddifference C0 between optical paths for anterior and posterior eyesegments. Then, the cornea is placed at the location F shown in FIG. 8,and at the same time, the removable total-reflection mirrors 302 and 303are quickly moved to obtain an OCT image of the human eye retina. OCTimages of the anterior and posterior eye segments are obtained afterquick imaging of the anterior and posterior eye segments, wherein themovement amount of the removable total-reflection mirrors 302 and 303 isX. They are respectively used to measure distance A between the peak ofcornea and the peak of image in the OCT image of the anterior eyesegment, and distance B between the peak of image and the macula foveain the OCT image of the posterior eye segment. Thus, length differencebetween optical paths for the anterior and posterior eye segments areC=C0±2X, wherein “±” is determined by moving the removabletotal-reflection mirrors 302 and 303 up or down, and C0 is a fixedlength difference between optical paths for the anterior and posterioreye segments. In the end, the optical length of human eye axis isL=B+C−A. That is, the optical length of eye axis is equal to distance Bbetween the peak of image and the macula fovea in the OCT image of theposterior eye segment plus length difference between optical paths forthe anterior and posterior eye segments minus distance A between thepeak of cornea and the peak of image in the OCT image of the anterioreye segment.

It should be made clear that an ophthalmic optical coherence tomographysystem provided in an embodiment of the invention can further be used tomeasure the depth of anterior chamber. The method for measuring thedepth of anterior chamber has the same principle of the measurement ofeye axial length. When the system is performing anterior eye segmentimaging, an anterior surface of corneal in a cornea image in theanterior eye segment imaging optical path is collected, and the lengthof posterior eye segment imaging optical path is changed by adjusting aremovable total-reflection mirror, i.e. the second total-reflectionmirror 302 and the third total-reflection mirror 303, or a removableretroreflector in the optical path adjustment unit, so that a surface ofcrystalline lens is measured to obtain an optical depth of anteriorchamber, the optical depth of anterior chamber being a distance betweenthe cornea and an anterior surface of crystalline lens, wherein theanterior surface of corneal is obtained with a anterior eye segmentimaging system and the anterior surface of crystalline lens is obtainedwith a posterior eye segment imaging system.

Based on the obtained optical depth of anterior chamber, the depth ofanterior chamber can be obtained, wherein the depth of anterior chamberis dividing the optical depth of anterior chamber by the refractiveindex of the anterior chamber.

It should be made clear that an ophthalmic optical coherence tomographysystem provided in an embodiment of the invention can further be used tomeasure the thickness of crystalline lens. When the system is performinganterior eye segment imaging, a cornea image in the anterior eye segmentimaging optical path is collected, and the length of posterior eyesegment imaging optical path is changed by adjusting a removabletotal-reflection mirror or a removable retroreflector in the opticalpath adjustment unit, so that a posterior surface of crystalline lens ismeasured with the posterior eye segment imaging optical path. Then, adistance between the cornea and the posterior surface of crystallinelens is obtained. An optical thickness of the crystalline lens isobtained by subtracting the distance by the optical depth of anteriorchamber.

Optionally, the anterior surface of crystalline lens is scanned with theanterior eye segment imaging optical path and concurrently, theposterior surface of crystalline lens is collected with the posterioreye segment imaging optical path, to obtain the optical thickness of thecrystalline lens. The optical thickness of the crystalline lens is equalto subtracting the posterior surface of crystalline lens collected withthe posterior eye segment imaging optical path by the anterior surfaceof crystalline lens scanned with the anterior eye segment imagingoptical path.

Based on the optical thickness of crystalline lens, the thickness ofcrystalline lens can be obtained, wherein the thickness of crystallinelens is dividing the optical thickness of crystalline lens by therefractive index of the crystalline lens.

It should be made clear that in the optical paths for anterior andposterior eye segments, in order to measure the anterior and posteriorsurfaces of the crystalline lens, lens may be inserted in any one orboth of the optical paths for anterior and posterior eye segments tochange the positions of the optical path focal points, so as to make thefocal points of the optical paths are just located on the anterior andposterior surfaces of the crystalline lens.

A person having ordinary skills in the art can realize that part orwhole of the processes in the methods according to the above embodimentsmay be implemented by a computer program giving instructions to relevanthardwares. The program may be stored in a computer readable storagemedium. When executed, the program may comprise processes in theabove-mentioned embodiments of methods. The storage medium may be amagnetic disk, an optical disk, a Read-Only Memory (ROM), a RandomAccess Memory (RAM), et al.

The above descriptions are preferred embodiments of the invention. Itshould be pointed out that a person having ordinary skills in thepresent technical field will be able to make improvements andmodifications within the spirit of the principle of the invention. Theimprovements and modifications should also be incorporated in theprotection scope of the invention.

1. An ophthalmic optical coherence tomography system, comprising: an OCTinterferometer primary module and a sample arm module, wherein the OCTinterferometer primary module comprises an OCT light source, a fibercoupler, a reference arm, a detection module, an X-direction scanningunit, and a Y-direction scanning unit; the sample arm module comprisesan anterior eye segment imaging module and a posterior eye segmentimaging module; and wherein: light output by the OCT light source isprovided to the sample arm module and the reference arm via the fibercoupler; the reference arm reflects the light received by the referencearm to the fiber coupler; the Y-direction scanning unit is rotatable;when the Y-direction scanning unit is at a first rotation angle, theY-direction scanning unit reflects the light received by the X-directionscanning unit into the anterior eye segment imaging module; when theY-direction scanning unit is at a second rotation angle, the Y-directionscanning unit reflects the light received by the X-direction scanningunit into the posterior eye segment imaging module; the fiber couplerreceives light scattered back by the sample arm, and the received lightinterferes with the light reflected back by the reference arm; and thedetection module is used for detecting the interfered light.
 2. Thesystem as claimed in claim 1, wherein the anterior eye segment imagingmodule comprises: a total-reflection mirror, a rotatable-adjustabletotal-reflection mirror, a dichroic mirror, and a fundus lens, andwherein: when the Y-direction scanning unit is rotated at the firstrotation angle, the Y-direction scanning unit reflects the lighttransmitted from the X-direction scanning unit to the total-reflectionmirror; the total-reflection mirror reflects the light to therotatable-adjustable total-reflection mirror; the rotatable-adjustabletotal-reflection mirror is rotatably adjusted correspondingly to arotation of the Y-direction scanning unit and cooperates with theY-direction scanning unit to reflect the light transmitted on therotatable-adjustable total-reflection mirror to the dichroic mirror; thedichroic mirror reflects the light to the fundus lens; and the light istransmitted through the fundus lens into a human eye to be examined. 3.The system as claimed in claim 2, wherein the anterior eye segmentimaging module further comprises at least one relay lens, and wherein:the at least one relay lens is between the Y-direction scanning unit andthe total-reflection mirror; and in this case, when the Y-directionscanning unit is rotated at the first rotation angle, the Y-directionscanning unit reflects the light from the X-direction scanning unit tothe total-reflection mirror via the relay lens; or the at least onerelay lens is between the total-reflection mirror and therotatable-adjustable total-reflection mirror; and in this case, thetotal-reflection mirror reflects the light from the X-direction scanningunit to the rotatable-adjustable total-reflection mirror via the relaylens.
 4. The system as claimed in claim 1, wherein the posterior eyesegment imaging module comprises: an optical path adjustment unit, arefraction adjustment unit, a rotatable-adjustable total-reflectionmirror, a dichroic mirror, and a fundus lens, and wherein: when theY-direction scanning unit is rotated at the second rotation angle, theY-direction scanning unit reflects the light transmitted from theX-direction scanning unit to the optical path adjustment unit; theoptical path adjustment unit reflects the light to therotatable-adjustable total-reflection mirror via the refractionadjustment unit; the rotatable-adjustable total-reflection mirror isrotatably adjusted correspondingly to the rotation of the Y-directionscanning unit and cooperates with the Y-direction scanning unit toreflect the light transmitted on the rotatable-adjustabletotal-reflection mirror to the dichroic mirror; the dichroic mirrorreflects the light to the fundus lens; and the light is transmittedthrough the fundus lens into the human eye to be examined.
 5. The systemas claimed in claim 1, further comprising: an iris imaging module, whichcomprises: a fundus lens, a dichroic mirror, an iris dichroic mirror, anobjective lens, and a camera, wherein, when the light output by thelight source is transmitted onto a cornea of a human eye to be examinedand is reflected by the cornea, the reflected light is transmitted tothe iris dichroic mirror through the fundus lens and the dichroicmirror; the iris dichroic mirror reflects the light to the objectivelens; and the reflected light is transmitted to the camera via theobjective lens and is taken by the camera.
 6. The system as claimed inclaim 1, further comprising a fixation optical module, wherein: thefixation optical module comprises: a fixation device, a lens, atotal-reflection mirror, a refraction compensating lens, a dichroicmirror, and a fundus lens; after focalized by the lens, the light fromthe fixation device is reflected to the refraction compensating lens bythe total-reflection mirror, transmitted to the iris dichroic mirror inthe iris imaging module via the refraction compensating lens,transmitted to the dichroic mirror and the fundus lens through the irisdichroic mirror, and transmitted through the fundus lens into a humaneye to be examined.
 7. The system as claimed in claim 4, wherein theoptical path adjustment unit comprises four total-reflection mirrors,and wherein two of the total-reflection mirrors are fixed, and the othertwo of the total-reflection mirrors are removable total-reflectionmirrors; during adjustment of optical path, the optical path is adjustedby keeping the two of the total-reflection mirrors fixed and moving theother two removable total-reflection mirrors.
 8. The system as claimedin claim 4, wherein the optical path adjustment unit further comprisestwo total-reflection mirrors and a removable retroreflector; and duringadjustment of optical path, the optical path is adjusted by keeping thetwo total-reflection mirrors fixed and moving the removableretroreflector.
 9. The system as claimed in claim 1, wherein thetotal-reflection mirror in the Y-direction scanning unit is agalvanometer.
 10. The system as claimed in claim 6, wherein the fixationdevice in the fixation optical module comprises an LCD or an OLED. 11.The system as claimed in claim 7, wherein an adjustment amount by theoptical path adjustment unit is obtained by a location sensor, thelocation sensor being fixed on the removable total-reflection mirror orthe removable retroreflector in the optical path adjustment unit.
 12. Amethod for quick switching to realize anterior and posterior eyesegments imaging, comprising: reflecting light transmitted from aX-direction scanning unit to a total-reflection mirror with aY-direction scanning unit when the Y-direction scanning unit is rotatedat the first rotation angle; reflecting the light to arotatable-adjustable total-reflection mirror with the total-reflectionmirror, the rotatable-adjustable total-reflection mirror being rotatablyadjusted correspondingly to a rotation of the Y-direction scanning unitand cooperating with the Y-direction scanning unit to reflect the lighttransmitted on the rotatable-adjustable total-reflection mirror to adichroic mirror; reflecting the light to the fundus lens with thedichroic mirror; transmitting the light through the fundus lens into ahuman eye to be examined; reflecting the light transmitted from theX-direction scanning unit to an optical path adjustment unit with theY-direction scanning unit when the Y-direction scanning unit is rotatedat a second rotation angle; reflecting the light to therotatable-adjustable total-reflection mirror via a refraction adjustmentunit with the optical path adjustment unit, the rotatable-adjustabletotal-reflection mirror being rotatably adjusted correspondingly to therotation of the Y-direction scanning unit and cooperating with theY-direction scanning unit to reflect the light transmitted on therotatable-adjustable total-reflection mirror to the dichroic mirror;reflecting the light to the fundus lens with the dichroic mirror; andtransmitting the light through the fundus lens into the human eye to beexamined.
 13. The method as claimed in claim 12, comprising: when thesystem is performing anterior eye segment imaging, obtaining an opticalpath length that the light travels after leaving the fiber and beforereaching a cornea of the human eye to be examined in the anterior eyesegment imaging, the optical path length being a fixed length ofanterior eye segment optical path plus a distance A between a peak ofthe cornea and a peak of image in an OCT image of anterior eye segment,wherein the fixed length of anterior eye segment optical path is anintrinsic parameter of the system, and the distance A between the peakof the cornea and the peak of image in the OCT image of anterior eyesegment is obtained by analyzing the OCT image; when the system isperforming posterior eye segment imaging, obtaining an optical pathlength that the light travels after leaving the fiber and beforereaching a retina of the human eye to be examined in the posterior eyesegment imaging, the optical path length being a fixed length ofposterior eye segment optical path plus an optical path adjustmentamount plus a distance B between a peak of image and a macula fovea inan OCT image of posterior eye segment, wherein the fixed length ofposterior eye segment optical path is an intrinsic parameter of thesystem, and the distance B between the peak of image and the maculafovea in the OCT image of posterior eye segment is obtained by analyzingthe OCT image; calculating a difference between the optical path lengthobtained in the anterior eye segment imaging and the optical path lengthobtained in the posterior eye segment imaging, and obtaining an opticallength of examined eye axis, wherein the optical length of eye axis is:the sum of the fixed length of posterior eye segment optical path plusthe optical path adjustment amount plus the distance B between the peakof image and the macula fovea in the OCT image of posterior eye segmentminus the sum of the fixed length of anterior eye segment optical pathplus the distance A between the peak of the cornea and the peak of imagein the OCT image of anterior eye segment.
 14. The method as claimed inclaim 12, comprising: when the system is performing anterior eye segmentimaging, collecting an anterior surface of corneal in a cornea image inthe anterior eye segment imaging optical path, and changing the lengthof posterior eye segment imaging optical path by adjusting a removabletotal-reflection mirror or a removable retroreflector in the opticalpath adjustment unit, so that a surface of crystalline lens is measuredto obtain an optical depth of anterior chamber, the optical depth ofanterior chamber being a distance between the cornea and an anteriorsurface of crystalline lens, wherein the anterior surface of corneal isobtained with a anterior eye segment imaging system and the anteriorsurface of crystalline lens is obtained with a posterior eye segmentimaging system.
 15. The method as claimed in claim 12, comprising: whenthe system is performing anterior eye segment imaging, collecting acornea image in the anterior eye segment imaging optical path; changinga length of posterior eye segment imaging optical path by adjusting aremovable total-reflection mirror or a removable retroreflector in theoptical path adjustment unit, so that a posterior surface of crystallinelens is measured with the posterior eye segment imaging optical path;obtaining a distance between the cornea and the posterior surface ofcrystalline lens; and obtaining an optical thickness of the crystallinelens by subtracting the distance by the optical depth of anteriorchamber; or scanning an anterior surface of crystalline lens with theanterior eye segment imaging optical path and concurrently collectingthe posterior surface of crystalline lens with the posterior eye segmentimaging optical path, to obtain the optical thickness of the crystallinelens, the optical thickness of the crystalline lens being equal tosubtracting the posterior surface of crystalline lens collected with theposterior eye segment imaging optical path by the anterior surface ofcrystalline lens scanned with the anterior eye segment imaging opticalpath.
 16. The system as claimed in claim 2, wherein the total-reflectionmirror in the Y-direction scanning unit is a galvanometer.
 17. Thesystem as claimed in claim 3, wherein the total-reflection mirror in theY-direction scanning unit is a galvanometer.
 18. The system as claimedin claim 4, wherein the total-reflection mirror in the Y-directionscanning unit is a galvanometer.
 19. The system as claimed in claim 8,wherein an adjustment amount by the optical path adjustment unit isobtained by a location sensor, the location sensor being fixed on theremovable total-reflection mirror or the removable retroreflector in theoptical path adjustment unit.